Compression combustion engines (Diesel) have gained popularity due to their high torque and excellent fuel mileage compared to spark ignited gasoline engines. Generally, the increased fuel efficiency of Diesel, however, results in higher NOx and particulate matter emissions.
As the awareness of the danger NOx emissions and Diesel soot presents to health collides with the need for greater fuel efficiency that Diesel engines provide, regulations have been enacted curbing the amount of Diesel soot permitted to be emitted. To meet these challenges, expensive soot filters and aftertreatments (e.g., three way catalytic converters; selective reduction catalyst ‘addition of urea’) have been used as well intricate engine control and fuel injection. It has been estimated that these pre and post-treatments each equal to ⅓ the cost of a Diesel engine (i.e., ⅔s of the cost of the Diesel engine is related in some way to reduction of emissions). In addition, as the regulations become ever more stringent, the fuel efficiency of Diesel engines is reduced all the while Diesel fuel gets substantially more expensive.
Accordingly, it would be desirable to provide a method of operating a compression ignition engine that overcomes one or more of the problems of the prior art such as one of those described above (e.g., elimination of pre and aftertreatment while meeting present and future regulations).